BRAF and melanoma: Although vemurafenib has demonstrated some promising clinical activity in patients with BRAFV600E-expressing PTC, responses are less common and less impressive than responses observed in BRAFV600E melanoma, with an ORR of only 30%-40% 5, 46.The MAPK and PI3K pathways are downstream signaling pathways of RTKs, and BRAF inhibitors have limited effects on the reactivated PI3K/AKT pathway.